79 research outputs found
quantification of the foreign body reaction by means of a miniaturized imaging window for intravital nonlinear microscopy
Brand new biomaterials, intended to be used on humans, must undergo in vivo quantification standardized, expensive and unethical procedures mainly based on histopathological analysis, from dissections, as defined by the ISO 10993 normative set. The aim is to prove the biomaterials biocompatibility. There exist no methods based on intravital microscopy able to satisfy the normative quantification requirements both reducing the number of employed animals and related costs. We developed a miniaturized imaging window, the Microatlas, which allows subcutaneous repeated observations in vivo of the foreign body reactions, for example to the implantation of a biomaterial. Confocal and twophoton microscopy inspections at Microatlas implantation sites demonstrated growth of the recipient tissue inside the microgrids both with micro vascularization formation and collagen generation. In conclusion, the Microatlas guided in vivo a quantifiable localized reaction inside its microscaffold, both in terms of cell repopulation, collagen and capillary formation as a probable foreign body reaction
Prolonged contact with dendritic cells turns lymph nodeâresident NK cells into antiâtumor effectors
Abstract Natural killer (NK) cells are critical players against tumors. The outcome of antiâtumor vaccination protocols depends on the efficiency of NKâcell activation, and efforts are constantly made to manipulate them for immunotherapeutic approaches. Thus, a better understanding of NKâcell activation dynamics is needed. NKâcell interactions with accessory cells and trafficking between secondary lymphoid organs and tumoral tissues remain poorly characterized. Here, we show that upon triggering innate immunity with lipopolysaccharide (LPS), NK cells are transiently activated, leave the lymph node, and infiltrate the tumor, delaying its growth. Interestingly, NK cells are not actively recruited at the draining lymph node early after LPS administration, but continue their regular homeostatic turnover. Therefore, NK cells resident in the lymph node at the time of LPS administration become activated and exert antiâtumor functions. NKâcell activation correlates with the establishment of prolonged interactions with dendritic cells (DCs) in lymph nodes, as observed by twoâphoton microscopy. Close DC and NKâcell contacts are essential for the localized delivery of DCâderived ILâ18 to NK cells, a strict requirement in NKâcell activation
Accumulative Difference Image Protocol for Particle Tracking in Fluorescence Microscopy Tested in Mouse Lymphonodes
The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done
Gold nanostars for superficial diseases: A promising tool for localized hyperthermia?
A review about the use of the photothermal effect exerted by gold nanostars in superficial deseases therapie
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